Currently at https://taginfo.openstreetmap.org/keys/highway#values there are 44k of these worldwide, so it's a frequently used value. Usage is spread evenly across the world; it's not a value that is used more commonly by some OSM communities to express that concept than others. It's documented at https://wiki.openstreetmap.org/wiki/Tag%3Ahighway%3Draceway .
It would add value to a general purpose map style that may want to use the Shortbread schema.
If added to a future version of the schema that addition would be extremely unlikely to affect existing clients, since they will mostly select highways to show by value ("only motorway", "only footway" etc. rather than "all highway types other than tertiary").
It would make sense to add it to linear layers
https://shortbread-tiles.org/schema/1.1/#layer-streets
https://shortbread-tiles.org/schema/1.1/#layer-street_labels
Currently at https://taginfo.openstreetmap.org/keys/highway#values there are 44k of these worldwide, so it's a frequently used value. Usage is spread evenly across the world; it's not a value that is used more commonly by some OSM communities to express that concept than others. It's documented at https://wiki.openstreetmap.org/wiki/Tag%3Ahighway%3Draceway .
It would add value to a general purpose map style that may want to use the Shortbread schema.
If added to a future version of the schema that addition would be extremely unlikely to affect existing clients, since they will mostly select highways to show by value ("only motorway", "only footway" etc. rather than "all highway types other than tertiary").
It would make sense to add it to linear layers
https://shortbread-tiles.org/schema/1.1/#layer-streets
https://shortbread-tiles.org/schema/1.1/#layer-street_labels